Inadequate access to timely information at the moment of decision-making is a well-documented proximal cause of medical errors. We hypothesize that when using a clinical information system (CIS), nurses and physicians encounter specific information needs that can be predicted, based on the information they are reviewing. We hypothesize that providing links to on-line resources designed to resolve those needs, can decrease the rate at which information seeking is deferred and increase the rate at which information seeking is successful. We will study this problem using "infobuttons"; programs that use context-specific information to anticipate information needs and automate retrieval from appropriate resources. We have built, tested and deployed infobuttons with positive anecdotal results. We believe it is now time to study them formally by: a) Studying information needs that arise when clinicians look at data in a CIS; b) Building infobuttons that address those specific needs; c) Develop a mechanism to support institution independent integration of infobuttons into a CIS and; d) Studying the ability of such infobuttons, once integrated into a working CIS, to improve access to information. We will directly observe clinicians, with an unobtrusive "portable usability laboratory", as they use a Web-based CIS in the routine course of patient care. We will ask them to "think aloud" about their information needs, capturing what they say and do on videotape. We will analyze the interactions to determine, for a given context, the information needs most likely to arise. We will then construct infobuttons to automate the retrieval of specific information relevant to specific needs. The infobuttons will be integrated into the CIS, using an "Infobutton Manager" that will be automated and data-driven while preserving the institution-independent nature of the infobuttons. We will then study clinicians' use of infobuttons to answer the following questions: 1) What information needs arise when clinicians use a CIS? 2) Can institution-independent infobuttons be built that address context-specific needs? 3) Do infobuttons improve access to information during clinical practice?